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How Astronauts Stay Fit

Picture of Shuttle Endeavour delivering the advanced Resistive Exercise Device to the international space station.

A CNN article looked at how astronauts stay fit in space and on earth. Research shows that floating around in zero-G can have some serious consequences for the human body, including the weakening of bones. In fact, studies have shown that space travelers can lose 1 to 2 percent of their bone mass each month on average, according to NASA.

One way that astronauts have been fighting bone loss is through strength training. And they're getting some help with a new machine delivered this week by the shuttle Endeavour, which docked with the international space station on Sunday.

The advanced Resistive Exercise Device, aRED for short, functions like a weight machine in a gym on Earth, except it has no conventional weights. Instead, it has vacuum cylinders -- canisters with air that have had a vacuum applied -- that provide concentric workloads up to 600 pounds, NASA says.

The device works somewhat like a bicycle pump, only in reverse, said Mark Guilliams, a NASA trainer. For example, if you are squatting, the vacuum gets pulled out as you stand up, and when you squat back down, the vacuum pulls the bar back to the normal position.

The international space station also is equipped with a treadmill and a bicycle, Guilliams said.

So what's the difference between exercising on Earth and working out on the international space station?

"When you run outside on Earth, you've got 195 pounds smacking against the pavement every time you take a step," said Anderson, who weighs 195 pounds on Earth. "In zero gravity, you're trying to use bungees to hold you down."

The treadmill has clip harnesses to hold an astronaut down, such that the fewer clips used, the more force acts around the legs, making running more difficult, he said.

Both before and after space travel, astronauts go through the same kinds of exercises familiar to athletes and others who exercise on Earth, Guilliams said -- aerobic activity such as running, and weight training. Astronauts training for a flight have scheduled exercise time two or three times a week for two hours each session, but in unscheduled time, they'll go for a run, he said.

For Clay Anderson, a NASA Astronaut who played football in college and has been athletic for much of his life, space travel was "physically easy." Space walks did get fatiguing because they required him to use his forearms, hands and upper body, which don't get much exercise on Earth.

"On Earth, you tend to use your big muscle group, and in space you tend to use your smaller muscle group, especially on a space walk when you use your forearms and your hands almost exclusively," he said.

Currently, an ongoing study is measuring how much astronauts who stay on board the international space station eat and exercise, Anderson said. The experiment will determine what kinds of dietary supplements astronauts should take in addition to the food they eat, and also the appropriate level and type of exercise they should get, he said.

"I think they're making some good strides in figuring out how to keep people healthy on a six- to nine-month trip to Mars," he said

I think is great research - we don't always see tools for such small groups of people. Astronauts, may represent a small population, but reaching even those that may not even be on our planet - is extremely important in the combat towards obesity. It goes to show that small minor details can make a big difference.